Optimization of gratings in a diffractive waveguide using relative-direction-cosine diagrams

Designing diffractive waveguides for head-mounted displays requires wide-angle conical diffraction analysis of multiple gratings. In this work, diffractive waveguide design using the relative direction cosine space, which extends the direction cosine space to a relative space involving refractive indices and can describe grating diffraction through various media, is demonstrated. A diffractive waveguide was fabricated with grating periods of 382 and 270 nm, which generated a monochromatic virtual image image in green light (520 nm). The maximum field of view was measured as 39 degrees with 0.5 degrees deviation from the center of view. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement